Felt drying apparatus



y 1954 K. o. LINDGREN FELT DRYING APPARATUS 4 Sheets-Sheet 1 Filed March4, 1952 EDIE/5% L 1' BY W *%m y 4, 1954 K. o. LINDGREN FELT DRYINGAPPARATUS 4 Sheets-Sheet 2 Filed March 4, 1952 INVENTOR Affys.

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FELT DRYING APPARATUS Filed March 4, 1952 4Sheets-Sheet 3 IN VEN TOR.

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Patented May 4, 1954 ITED STATES ATENT OFFICE FELT DRYING APPARATUSSweden Application March 4, 1952, Serial No. 274,712

Claims priority, application Sweden March 8, 1951 '7 Claims.

The present invention relates to felt drying drums for pa cr-makingmachines and more speci ally to dms of the type including an outer,freely rotatable device, and an inner stationary device which isco-axial with said rotatable device and forms a suction or pressurechamber, said rotatable device consisting of a, plurality of parallelcylindrical rolls which are journalled in two su' sorting end wallscomprised in said stationary a: section through said rotatable device,uniformly distributed on an arc, and further including at least oneguide roller, when said arc exceeds 180, to cause the felt to contactall of said rolls.

en paper is produced in paper-making machines the paper web, having amoisture content of about 70 to 65%, is conducted into a dryingapartment usually consisting of one or more groups of rotating, heateddrums. In the production of most of the existing paper qualities thickendless woolen felt webs, so-called drying felts, are used to press thepaper web against the surface of the drying drums. Through this pressingaction a favourable heat transfer from the drum to the paper web isobtained, and at the same time corrugation of the paper will beprevented and a glazed paper surface will be obtained, as well as otherdesirable effects.

The moisture absorbed by the felt upon pressing the paper web againstthe hot surfaces of the drums must be removed as completely as possible,and the felt is therefore usually conducted over separate steam-heatedfelt drying drums, although in recent times drying drums of thefirstmentioned type have begun to find utilization. For drying the feltthe necessary drying drum surface will usually be about 35% of the drumsurface necessary for drying the paper Web.

The present invention has for its objects to reduce the great and costlyneed of space necessary according to the felt drying method described inthe foregoing, and, in addition, to reduce the heat supply necessary forthe felt drying operation, as compared with prior methods, which isattained by increasing the efficiency of the heat transfer, to thedrying felt. Since, in prior paper-making machines, the felt drying drumsurface is often too small, the insertion of one or more apparatusaccording to this invention will enable, by a relatively small capitalinvestment, to obtain a materially increased machine capacity.

For the objects stated, according to the present invention, a feltdrying drum for paper-making machines of the type described in thebegince, the centers of said rolls being, in a crossning of the preambleis mainly characterized by the fact that said rolls are freely rotatableand adapted to be driven by the endless felt web embracing the same, andthat said suction or pressure chamber is completely closed, a peripheralwall for this chamber being, in a manner known per se, formed by theportion of said felt Web embracing said rolls, and the end walls of saidchamber being formed by two end plates, the chamber being at itsradially inner portion or bottom connected to a suction or pressureconduit of an air fan which is arranged to draw or feed, respectively, astream of heated air into said chamber, said airstream causing a vacuumor a super-atmospheric pressure, respectively, in said chamber anddrying said felt web when passing therethrough.

A specific embodiment of the invention will now be described by way ofexample in conjunction with the accompanying diagrammatical drawings.

In the drawings:

Fig. l is a plan view, partly broken away, of the drying drum.

Fig. 2 is an end view of the same.

Fig. 3 is a vertical longitudinal section through one end portion of thedrum.

Fig. i is a cross-section through the drum intermediate its ends.

The freely rotatable device embraced by the felt web I consists of aplurality, in this case six, cylindrical rolls 3 which are mounted intwo supporting end walls 2 comprised in the stationary device so as tobe freely rotatable therein, said rolls extending in parallelinterrelation and forming therebetween sufficiently wide gaps foradmitting heated drying air. The supporting end walls 2 are secured tothe machine stand 5 by means of brackets 4. In order to accommodatethermal expansion of the rolls 3 upon heating, the ends of the rims ofthe rolls project endwise into circular grooves 6 provided in thesurfaces of the end Walls 2 facing said rolls 3 forming therewith asimple labyrinth seal. Each end portion of each roller 3 is mounted onan internal antifriction bearing 7 the inner race of which is rigidlymounted on a stub shaft 8 secured in the end wall 2 and is retained by alocking nut 9, whilst the rim of the roll is, at each end, supportedinteriorly on the outer race of said bearing so as to be axiallydisplaceable thereon. A sealing and reinforcing diaphragm I0 is securedin the hollow roll 3 opposite the stub shaft 8, for instance by brazing.

The centers ll of the rolls 3 are, in a vertical 3 section through theset of rolls, uniformly distributed on an arc, and the angular distancealong this are between the centres of the two extreme rolls has to be atleast 180, said distance being in this instance about 220. When this areexceeds 180 a guide roller l2 has usually to be present in order tocause the felt web I to contact all of the rolls 3, as indicated in Fig.4.

The suction or pressure chamber l3 comprises two essentially sectorshaped, in axial section cup-shaped end plates or covers I4 theperipheral flanges of which are directed towards each other. The endcovers [4 are provided in their peripheral portions with arcuaterecesses l5 each one of which substantially sealingly embraces a portionof the periphery of a corresponding one of the rolls 3, as will be bestseen in Fig. 4. The outer peripheral surfaces it of the end covers I4situated between said recesses l5 are plane and parallel with atangential plane to the two adjacent rolls 3. The space between saidplane surfaces and the felt web I running tangentially over the rollsupon operation of the apparatus is occupied by sealing plates l'lperipherically connecting on to two adjacent rolls and extending axiallyover said plane surfaces to serve as supports for, and sealing membersat, the lateral edges of the felt web I. The sealing plates it maysuitably be made of bongo wood or the like.

The bottom of the suction or pressure chamber i3 is formed by alongitudinally extending wall is extending radially between the twoextreme rolls 3, the ends of said wall passing, with allowance forthermal expansion, in sealing rela-- tionship through elongated openingsor slots provided in the end plates or covers i l of chamber l3. Eachlongitudinal edge of said bottom wall 18 carries a detachable scraper [9in sealing contact with the corresponding roll 3 (Fig. 4). The bottomwall 18 has provided therein a suitable number of openings 20 capable ofpassing -he necessary rate of air flow, said openings setting thesuction or pressure chamber H3 in communication with a manifold ordistributor 2! extending along the outside of the bottom wall it and towhich the suction or pressure conduit 22 of the fan (not shown) isconnected.

In order to adapt the effective axial length of the drying drum to theslightly varying felt width, and also to any displacement of the feltweb l axially along the drum, an adjustment device is provided by whichthe end covers [4 with the sealing plates H for the edges of the felt imay be displaced by a suflicient amount longitudinally of the rolls 3.Said adjustment means comprises a plate or the like 23 rigidly attachedto each chamber end cover l4 and having a number of circular holesprovided with gaskets 24, the rolls 3 projecting through a correspondingone of said holes towards the adjacent one of the supporting end walls2. Plate 23 is, in addition, provided in its rim portion with a numberof guide holes by which the plate is guided on correspondinglongitudinally extending guide pins 25 which are rigidly secured to thecorresponding supporting end wall 2. To each cover M are, in addition,two or more guide pins secured, on which pins 30 guide sleeves 29rigidly connected to the bottom is slide upon axial displacement of saidend cover It. The adjustment means also includes an axially directedadjustment screw provided with an operating wheel 26 and being freelyrotatably and longitudinally displaceably connected with the platethreadedly interengaged with the supporting end wall 2. By turning thewheel 26 in one direction or the other, it will thus be possible todisplace the plate 23 with the gaskets 24 and the end cover It along therolls 3 in order to increase or reduce, respectively, the efiectivelength of the drum. To establish satisfactory sealing and dusttightenclosure of the ends of rolls 3 and other elements, a bellows istightly secured between the rim of .plate 23 and the rim of thesupporting end wall 2. To keep constant the position of sealing plate 24and end cover [4 relative to the lateral position of the edge of thefelt web I, the wheel 26 as shown might be substituted by a sprocketwheel, for example, which could receive operating impulses via a drivingchain and, for instance, a servo mechanism from a felt controllingmechanism incorporated in the machine, or from a manually adjustablecontrol drum.

It will be understood that the invention is not restricted to theembodiment described in the foregoing and illustrated in theaccompanying drawings since the same is susceptible of variousmodifications within the scope of the invention defined in and by theappended claims.

What I claim and desire to secure by Letters Patent is:

l. A felt drying apparatus for paper-making machines and including anouter, freely rotatable device to receive embraced thereon an endlessfelt web to be dried, an inner stationary device in coaxialinterrelation with said rotatable device, an air chamber defined withinwalls formed by said stationary device and by the portion of said feltweb embracing and rotatable device when received thereon, airdisplacement means connected to said chamber for causing an air streamto pass through said portion of said felt web in order to removemoisture therefrom, a plurality of parallel cylindrical rolls formingsaid rotatable device by being journalled in two supporting end wallsconirised in said stationary device, the centers of said rolls being, ina cross-sectional plane through said rotatable device, uniformly disuributed on an are less than 360, and means for causing said felt web tobe pressed into contact with all of said rolls, said rolls being freelyrotatable and driven by said endless felt web, said air chamber beingcompletely closed within said embracing portion of said felt web formingits peripheral wall, two opposite end plates forming the end walls ofsaid chamber, and a radially inner wall forming a bottom of saidchamber, and an air duct from said air displacement means being arrangedto pass a stream of heated air through said chamber wall forming portionof said felt web to dry the same when passing over said rotatable rolls.

2. Apparatus according to claim 1 comprising two substantiallysector-shaped, in axial section cup-shaped, end plates or covers havingtheir peripheral flanges directed towards each other, arcuate recessesin the peripheral portions of said end covers, each one of said recessesenlbracing in substantially gas-tight relation a pcrtion of theperiphery of a correspondin one of said rolls, the outer peripheralsurfaces of said end covers extending between said recesses being planeand parallel with a tangential plane to the two adjacent ones of saidrolls, the space between said plane surfaces and said felt web runningtangentially over said rolls being occupied by sealing platesperipherically connected on to adjacent rolls and extendinglongitudinally over 23 and thus with the end cover It, and being saidplane surfaces to serve as supports for, and

5 sealing members at, the lateral edges of said felt web.

3. Apparatus according to claim 1 in which said suction or pressurechamber includes a bottom wall extending radially outward between thetwo extreme ones of said rolls, the ends of said wall passing, withallowance for thermal expansion, in sealing relationship throughelongated openings or slots provided in said end plates or covers ofsaid chamber, each longitudinal edge of said bottom wall carrying adetachable scraper in sealing contact with the corresponding one of saidextreme rolls, and said bottom Wall having provided therein a pluralityof openings through which said chamber communicates with said suction orpressure conduit of said suction or pressure producing device.

4. Apparatus according to claim 1 comprising adjustment means by whichsaid end plates or covers of said chamber are displaceablelongitudinally of said chamber bottom and said rolls, whereby theefiective length of said apparatus may be adapted to any variations inthe width of said felt web and also to any displacement thereoflongitudinally of said rolls.

5. Apparatus according to claim 4 in which said adjustment meanscomprise a plate rigid with said chamber end cover, said last-mentionedplate being provided with circular holes each having therein a gasket,said rolls projecting through corresponding ones of said holes towardsthe adjacent one of said supporting end walls, said plate being furtherprovided with a plurality of guide holes in interengagement withcorresponding guide pins rigidly attached to said supporting end wall,and further with an adjustment screw having a control member and beingfreely rotatably and axially non-displaceably connected with said plate,said screw being threadedly connected with said supporting end wall andpassing axially therethrough.

6. Apparatus according to claim 4 comprising bellows means mountedtightly between the rim of said last mentioned plate and the rim of saidsupporting end wall.

7. Apparatus according to claim 4 comprising follow-up means foractuatin said control member of said adjustment screw from a controldevice comprised in said paper-making machine.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 442,229 Kaiser Dec. 9, 1890 2,572,268 Kuljian Oct. 23, 19512,574,833 Kuljian Nov. 13, 1951

